With the increasing integration and density of semiconductor devices in recent years, circuit wirings are becoming miniaturized, and the number of layers of multilayer wirings is increasing. To miniaturize circuit wirings while increasing the number of layers of multilayer wirings, it is required to accurately planarize the surfaces of semiconductor devices.
A well-known technique for planarizing the surfaces of semiconductor devices is CMP (Chemical Mechanical Polishing). A polishing apparatus for CMP includes a polishing table having a polishing pad attached thereto, and a top ring for holding a material to be polished (for example, a substrate such as a semiconductor wafer or the like, or various films formed on a substrate surface). In the polishing apparatus, the material to be polished is pressed against the polishing pad while the polishing table and the top ring are rotated, to thereby polish the material to be polished.
The polishing apparatus uses a rotary joint to supply fluids to rotating structures, such as the polishing table and the top ring. For example, the rotary joint is used to supply a cooling liquid to the polishing table so as to cool the polishing table. The rotary joint is also used when an optical film thickness sensor is installed inside the polishing table for detecting the film thickness of the material to be polished is detected by the sensor. In this case, the rotary joint is used to supply pure water to the polishing table, so as to surround the optical film thickness sensor with the pure water and thus improve detection accuracy. However, use of the rotary joint is not limited to the above examples. The rotary joint has a variety of other uses as a part of the polishing apparatus.
The rotary joint includes a rotating body that rotates on a rotating axis, a housing disposed so as to surround the rotating body, and a bearing disposed between the rotating body and the housing. The rotary joint supplies fluids to the polishing table or the top ring through fluid connection ports formed in the housing and fluid passages formed inside the rotating body.